Snivy is a proud and seductive Pokémon, and she also has a great observation. Furthermore, she has a sense of justice. When Iris' Emolga is causing mischief among Ash's Pokémon, she always mercilessly exposes Emolga's mischievous behavior by bringing her with her Vine Whip and to show it to Ash and his friends that she was responsible for stealing their apples, which makes Emolga angrily fed up, creating their heated rivalry.
Their heated rivalry is later demonstrated in Team Rocket's Shocking Recruit!, where Snivy was surprised to see Emolga was briefly recruited by Team Rocket and becomes furious when she thwarted her attempt to kidnap Iris' Axew by using her Vine Whip causing both of them to have a fight and they are mostly seen arguing each other during the fight which Meowth could not translate their language due to their bickering. Their fight is similar to Ash's Corphish and May's Torchic when they fight.
Even though she barely shows her emotions, she cares deeply for her friends. Still, she dislikes Trainers who don't fit her expectations, especially those who are selfish, which was a reason why she had left her former Trainer. This also happens in Evolution by Fire!, in which Snivy dislikes Shamus for abandoning Tepig and his cruelty which she convinces Tepig to fight his former trainer, even though he keeps his loyalty to him.
Snivy is also a risk taker like Ash's Boldore where she nearly sacrificed her life by tackling Tepig from getting a direct hit much like Boldore did to Cilan's Crustle and she is also the main reason for Tepig to regain composure and his evolution to Pignite to gain his confidence in fighting.
In Scraggy and the Demanding Gothita!, Snivy also dislikes Katharine's Gothita's bratty and demanding behavior when she takes a liking to Ash's Scraggy and her actions to other Pokémon. After she defeats her in battle, Snivy humiliates it by showing her beauty streak towards her.
She is also had a behavior of a femme fatale when using her Attract against male Pokémon which she demonstrated this to Pikachu, Oshawott and Tepig when Ash attempted to capture her. But it didn't affect Pidove due to both having the same gender, making her felt desperate to fight.
Snivy was caught by Ash and the gang, after she stole food from them. Ash then chased after Snivy, using each member of his team in turn to battle her, however the majority of his team (Pikachu, Oshawott and Tepig) were affected by Snivy's Attract, forcing Ash to recall each of them. It wasn't until Pidove offered to battle did Ash manage to hold his own Snivy, as her Attract had no effect on Pidove. Snivy broke out of the first Poké Ball attempt and fought back, but she decided that Ash was a worthy trainer and allowed Ash to catch her.
Snivy is used to fight a wild Gothitelle which is owned by Sally, the daughter of the Water Taxi Captain in the episode The Lost World of Gothitelle! when it manages to send Ash, Cilan and Iris to the lost world. Snivy becomes seriously desperate to fight until it was later interrupted by a present Sally whom she recognizes her Pokémon who helped her selling juice and cookies as a child. After both Sally and Gothitelle bonded together, the fog is completely gone due to its safekeeping of their memories.
She was sent out twice during Ash's five-on-five battle with Trip in A Rival Battle for Club Champ!. She first battled Trip's Servine and won with the help of her Attract. She then battled Trip's Frillish after Pidove was defeated, leaving her as Ash's only hope. Ash had no knowledge of Frillish's Cursed Body ability, Snivy endures Water Pulse easily, but the resulting confusion results in Frillish's Hex knocking her out.
In Emolga and the New Volt Switch!, she battled against Bianca's Pignite after Iris' Emolga summoned it using Volt Switch. It later develops a rivalry with Emolga, as she is unimpressed with Emolga's mischievous attitude. It continuously uses Vine Whip to bring Emolga back after she tries to escape and also when Snivy showed the gang who had caused the fight between Ash's Pokémon after Emolga steals all of their apples by fooling them using Attract causing her to get mad at her actions. However, despite this, Snivy saved Emolga (as well as Axew and Oshawott) from a wild Simisear. Therefore, she was reluctant to team up with Emolga to save the wild Simisear from a falling rock by breaking it with both Hidden Power and Leaf Storm combination. In the end, both Snivy and Emolga are not looking at each other due to their rivalry.
Ash used Snivy to battle against Trip's Servine again in Ash and Trip's Third Battle!. However, this time her Attract was blocked by Servine's Leaf Tornado and her Leaf Blade was overpowered by Servine's Cut.
In Cilan Versus Trip, Ash Versus Georgia!, Snivy was used against Georgia's Pawniard during the second round of the Don Battle Tournament, however, she struggled against the powerful Pokémon, having Attract fail when Pawniard also turned out to be female. However, she managed to defeat Pawniard in the next episode, by somehow using Leaf Blade to hit Pawniard dead-on while avoiding Guillotine and knocked her out with Leaf Storm.
In Battle for the Underground!, all of the Pokémon were captured by Team Rocket. Snivy used her vines to let out several of the groups Pokémon, all of which proved useful for making an escape. She also used her vines to switch the direction of the tracks, allowing the Pokémon to get away from Team Rocket's train car and their helicopter piloted by Doctor Zager.
In Dazzling the Nimbasa Gym!, Ash used Snivy against Elesa and her Emolga. Since they were both female, so Attract proved to be ineffective. While Snivy managed to hit it with Leaf Storm, Emolga finally defeated Snivy with several powerful Acrobatics and Aerial Ace attacks.
In Scraggy and the Demanding Gothita!, Snivy was happy to see Axew and Scraggy getting along despite them both losing in a battle. When Katharine's Gothita and Scraggy escaped and then followed by Axew in the middle of the night, Snivy followed them closely, and saves them from an attack caused by a wild Garbodor. She later fought Gothita in battle after revealing her dislike to her bratty and demanding attitude and to urge Scraggy to join in Katharine's side by trade. After Snivy defeated Gothita to make Ash won the battle and not to trade Scraggy to Katharine's other Pokémon, she humiliated her by showing her beauty streak, making her run away in a bratty manner and Katharine to chase her Pokémon.
In Battling the King of the Mines!, Snivy was used in a Gym battle against Clay's Palpitoad. She used Attract to immobilized it and then hitting it with Vine Whip and Leaf Blade and finally defeated it with Leaf Storm.
In Evolution by Fire!, Snivy was disgusted from Shamus, Tepig's former trainer. Snivy was the one who convinced Tepig to fight his former Trainer in battle and she also slapped Tepig's face with her Vine Whip to wake him up from his depression. During the tag battle, Snivy was attacked by both Shamus' Emboar and Heatmor's attacks which she glared Tepig by convincing him to fight back as he confidently agrees. Snivy managed to save Tepig from getting knocked out in the process from both of Emboar and Heatmor's Flare Blitz and Fire Spin combination, but her loss brought back his motivation and his evolution to Pignite to defeat both of Shamus' Pokémon with his newly learned Fire Pledge and a newly powerful Flame Charge to make Ash won the tag match and Snivy was happy for Pignite to their victory despite her severe injuries.
In Beauties Battling for Pride and Prestige!, she faced off against the Flower Garden Trio. Ash used Snivy up against Moira's Cinccino in a test of strength on a balance beam. She overpowers Cinccino and throws her into the mud, later her and Cinccino have a real battle and, although Cinccino gave her serious problems, she managed to defeat it.
In Cameron's Secret Weapon!, Snivy was the sixth Pokémon Ash chose to use during his Vertress Conference battle with Cameron, sending her out to face Cameron's Riolu. Riolu started the battle with a Vacuum Wave, which Snivy was easily able to dodge before attacking the Emanation Pokémon with Leaf Blade. While Riolu tried to struggle to his feet and almost fainted, the severe pain resulted in Riolu suddenly evolving into Lucario, a much more formidable opponent, who got his strength back. Snivy bombarded him with numerous brutal Vine Whips, but Lucario caught them and used Circle Throw, and finished her with Aura Sphere, leaving only Pikachu to battle the powerful foe.
In Team Plasma and the Awakening Ceremony!, she was used to battle against two Golurk controlled by Colress. Despite the notable size difference, Snivy is able to bring them down with Leaf Storm, but she had to be returned to her Poké Ball when Colress turned his mind control device on them.
In The Pirates of Decolore!, Snivy teams up with Ash's Pignite against Croconaw and Azumarill after they were revealed as the Pokémon who were abandoned by their horrible trainers which Snivy is detested for and she was the responsible for making a double battle against them if they won the pirates will stop stealing someone's food. She is the only one can beat them both using both her Vine Whip and Leaf Storm to deal a super effective damage allowing Pignite to defeat them with Fire Pledge.
In Team Rocket's Shocking Recruit!, Snivy's heated rivalry with Iris' Emolga is demonstrated after the latter was briefly recruited by Team Rocket. Snivy eventually thwarted Emolga's attempt on kidnapping Iris' Axew using her Vine Whip causing her to get mad and both begins to fight head on with Snivy destroys Emolga'a Hidden Power with her Leaf Blade while Emolga retaliates by damaging Snivy with her Discharge. Emolga accidentally hits a sleeping wild Exploud with her Hidden Power when Snivy dodges the attack. Both female Pokémon continues to fight only to be stopped by Ash when Team Rocket attempts to attack the group as Meowth could not translate them due to their bickering. After revealing the misunderstanding between Iris and Emolga and both Axew and Emolga are captured by Team Rocket to let them fight a wild Exploud inside the mirrored box. Snivy teams up with Ash's Charizard and Iris' Dragonite to break the box to rescue both and Ash's Pikachu who is caught in the net. Snivy also manage to beat both James' Yamask and Jessie's Woobat with Vine Whip and Leaf Storm and cutting the net using Leaf Blade to free Pikachu. After Team Rocket is blasted off by a wild Exploud's Thunder Punch who is also getting blasted off with them from Dragonite's Dragon Rush, Snivy finally gains her mutual respect to her rival Emolga after knowing of her misunderstanding with Iris and she watches Emolga and Axew are playing together.
After Ash's Unova adventure was over, Snivy was released among with Pignite, Scraggy, Oshawott and Charizard in Professor Oak's laboratory in the episode The Dream Continues! after Ash's Bulbasaur releases its Solar Beam in a shining multiple of sparkles to gain attention of other Ash's Unova Pokémon such as Unfezant, Krookodile, Boldore and Palpitoad. When Team Rocket arrives to capture Pikachu and other Pokémon, Snivy is among the rest of the Unova Pokémon along with Charizard and Pikachu to blast them off with their powerful attacks. Snivy is last seen very happy with the other Pokémon to see Team Rocket blasted off for good and resided at Professor Oak's lab.
- She shares traits with Ash's other Grass-type Starter Pokémon: being a protector like Bulbasaur, being female like Bayleef, being a prime battler like Sceptile and taking charge like Torterra, specifically when the latter was a Turtwig. She, like Bulbasaur, also never evolved.
- All of Snivy's Grass type moves are also known by Ash's other Grass-type Starters.
- Snivy has developed a rivalry with Iris' Emolga.
- Interestingly, they are both the only female Pokémon currently on the main cast that know Attract.
- The two have somewhat opposite personalities; Snivy is calm, collected, mature and willing to fight her own battles no matter how tough her opponent may be, while Emolga is childish, deceptive, lazy and unwilling to battle seriously and/or tricks/forces others to battle for her (by using Volt Switch).
- Snivy is Ash's first Unova Starter Pokémon confirmed to be female. Snivy can be also count as Ash's second female Unova Pokémon after Unfezant, due to both genders revealed in the same episode where Snivy was introduced and captured, and at time when Unfezant was Pidove.
- Snivy's capture marks the first time since Johto that Ash has captured all three of a region's starters.
- When Snivy unleashes her Leaf Blade from her tail, it resembles Ash's Treecko's Pound during execution.
At Oak's Lab
At Kukui's house
At Cerise Laboratory